3.1 will include beta over-the-air support for Treo and PocketPC devices. Blackberry currently supported with desktop sync via the Outlook Connector for calendar/contacts and you can use IMAP for over-the-air email.

We are also prototyping a light-weight web-ui for older browsers, console type machines, or low bandwidth situations (dial-up, wireless, etc). Assuming this works well it will be included in a future release.

Looking for new beta users -> Co-Founder of Acompli. Previously worked at Zimbra (and Yahoo! & VMware) since 2005.